This invention pertains to mechanisms for controlling height of upper frames in seat suspensions such as those commonly used in vehicles, and more particularly in seat suspensions having air springs.
The heights of vehicle seats having air springs are adjusted to desirable levels by drivers operating adjusting levers attached to respective upper frames of the seat suspensions. Unless air is automatically added to or bled from an air spring of a seat of this type, the occupancy of the seat by a driver of different weight will change the height from the selected desired height according to the degree of compression of air in the air spring.
According to U.S. Pat. No. 3,999,800 issued to Roger Paul Penzotti on Dec. 28, 1976, an adjusting lever for controlling addition and bleeding of air from an air spring is pivotally attached to an upper frame of a seat suspension to provide both manual selection of a desired height and automatic restoration to the desired height. The adjusting lever is manually set at different predetermined angles corresponding to different desired heights, and while at the set angle and as the weight on the seat is changed, the entire lever is moved vertically with the upper frame to restore the height of the seat. In this prior arrangement, quite long levers are shown to operate a plunger of an air valve.
The height of another vehicle seat that has been available on the market is controlled by a readily available air valve having a control arm about 7 inches (178 mm) long extending horizontally and rearwardly between upper and lower frames of a seat suspension. The housing of the air valve is secured to the lower frame, and the distal end of the control arm is connected by a vertical link to a control lever connected to the upper frame. As described in the Penzotti patent, the control lever can be turned to different positions about a pivot connected to the upper frame for selection of desired heights, and a change in distance between the upper frame and the lower frame controls the air valve to add air to or to bleed air from the air spring for restoring the selected desired height.